The first thing I like to do in the morning as I wake up is to read new emails in the Galaxy S. I refresh my Gmail account in the Gmail app, the mails show up, I read them and everything works smoothly.

However, when I get to work and open my Gmail account on the desktop, all the emails I had previously read show up as "unread". Why does this happen? I have Google account syncronization off, is this the reason? Doesn't this only affect the incoming email?